This invention relates to a rotary magnetic recording-reproducing apparatus, and more particularly to a rotary magnetic recording-reproducing apparatus for reproducing information recorded in a rotary magnetic recording medium such as a magnetic disc. Especially, this invention relates to a rotary magnetic recording-reproducing apparatus wherein information recorded on tracks formed concentrically on the magnetic disc is reproduced with a tracking servo being applied thereto.
Recently, there has been developed an electronic still camera system wherein an image pickup device such as a solid state image sensing device or an image pickup tube is combined with a recording device using an inexpensive magnetic disc as a recording medium which has comparatively high memory capacity, a subject is still-photographed purely electronically and recorded onto a rotating magnetic disc, and the reproduction of an image is carried out by a television, a printer or the like, which are provided separately.
However, the recording medium used in the above-described magnetic recording, namely, the magnetic disc, tends to cause a tracking failure due to anisotropy, eccentricity, thermal expansion and the like. In consequence, there is such a disadvantage that a track adjacent a predetermined track is scanned during reproduction, whereby crosstalk is caused.
To obviate this disadvantage, there is a method wherein a tracking signal is recorded with a tracking servo being applied during recording of information, and during reproduction the tracking servo is applied by use of the tracking signal. However, it is impracticable to provide a tracking servo mechanism requiring highly accurate control on a recording apparatus which is compact in size and light in weight, such as a camera.
Thus, there is a method wherein, as the recording system, a guard band system or an FM azimuth system is adopted, and the tracking failure occurring to some extent during reproduction is compensated in such a manner that is reproducing head does not scan the adjacent track and, even if the reproducing head scans, the reproducing head does not pick up a signal of the adjacent track.
Along with the above, a so-called peak searching system is used, wherein during recording a recording head is transferred at a predetermined track pitch by a stepping motor without the tracking servo being applied and during reproduction envelopes of output signals of respective tracks are detected, the optimal track is discriminated from a position of peak, and the tracking servo is applied.
In the rotary magnetic recording used in the electronic still camera system, 50 tracks are recorded on a disc having a diameter as small as about 50 mm at a track pitch of about 100 .mu.m, i.e. a track width of about 50.about.60 .mu.m and a guard band width of about 50.about.40 .mu.m, for example. In the recording or reproducing apparatus, this magnetic disc is rotated at a constant speed of 3600 rpm, for example, and image signals are recorded or reproduced at a field or frame speed.
The above-described compact magnetic disc, being thin and having a small diameter, is normally housed in a mold package (hereinafter referred to as a "disc pack") made of plastics, etc. for handling. Namely, each disc pack is loaded in a loading position of a recording or reproducing apparatus, whereby the magnetic disc housed in the disc pack is rotatably driven for recording or reproduction.
The above described disc pack is loaded in a bucket of the rotary magnetic recording-reproducing apparatus, and the loading is completed by closing the bucket. If an operator accidentally loads an unrecorded disc pack and moves the magnetic head, then a reproduced image does not appear on a display screen as a matter of course. In this case, the operator should be informed of whether this condition has been caused by an unrecorded disc pack or by a problem with the rotary magnetic recording-reproducing apparatus.
With the above-described rotary magnetic recording -reproducing apparatus, there are cases where during reproduction the operator accidentally presses a reverse switch to feed the magnetic head in the reverse direction for reproduction from a first recording track, and the operator erroneously presses a forward switch to feed the magnetic head in the forward direction for reproduction from the final track. In such cases, it becomes necessary to inform the operator that the track and, even if the magnetic head is further moved, the reproduction cannot be performed.
Furthermore, if the operator accidentally closes the disc pack in the non-loaded state and the forward or the reverse key is operated to move the magnetic head, a reproduced image does not appear on the display screen as a matter of course. In this case, it becomes necessary to inform the operator of whether this condition has been caused by misoperation in loading, due to non-loading of the disc pack, or by a problem with the rotary magnetic recording-reproducing apparatus.